BOSTON, MASSACHUSETTS. Endothelial dysfunction is a disorder of the lining of the blood vessel and
manifests itself by reduced arterial blood flow and greater platelet adhesiveness. It is believed to be a
precursor of atherosclerosis and is a common feature of cardiovascular disease.
Researchers at the Boston University School of Medicine and the Linus Pauling Institute now report that
drinking black tea reverses endothelial dysfunction in patients with coronary artery disease. Their
experiment involved 50 patients who consumed either 450 ml of tea or 450 ml of water two hours before
having their brachial blood flow measured. The blood flow increased by 57 per cent in the tea group, but no
significant increase was seen in the water group. At another time the patients were assigned to drink either
900 ml of tea or 900 ml of water daily for four weeks. The blood flow increased by 58 per cent in the tea
group, but no significant increase was seen in the water group. An equivalent dose of caffeine (200 mg)
also had no effect on endothelial function. The researchers conclude that short- and long-term black tea
consumption reverses endothelial dysfunction in coronary heart disease patients. They believe the effect is
attributable to the flavonoids found in tea.
Duffy, Stephen J., et al. Short- and long-term black tea consumption reverses endothelial dysfunction in
patients with coronary artery disease. Circulation, Vol. 104, July 10, 2001, pp. 151-56